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一个利用SDL语言来实现svgalib函数的示例程序

* Changes between versions   -*- mode:indented-text; mode:outline-minor -*-

This file (NEWS) documents the significant changes between all
versions of zgv, with the newest changes first.


* Changes in zgv 5.9

** New features

Added SDL mouse support. Thanks to Dimitar Zhekov for this.


** Bugfixes

Added width/height limits to all picture readers, 32767x32765 is now
the maximum image size supported (essentially consistent with xzgv).
This is a crude (albeit effective) fix for several reported overflow
bugs, which had previously meant that zgv could be exploited to run
commands as the user when viewing a maliciously-formatted file. Thanks
to Luke Macken for letting me know about the problems. I suppose I
should also thank "infamous41md" for publishing the original
advisory/exploit, even if he didn't bother emailing me or anything.

Added more multiple-image GIF brokenness checks than before.
Previously it was possible to get a segfault with the `right' file,
despite there already being various range checks. Thanks to Mikulas
Patocka for spotting this.

Fixed a problem with freeing memory when a GIF fails to load. Thanks
to Mikulas Patocka for the fix.

Fixed a possible hang when reading GIF files with corrupted extension
blocks. Thanks to Mikulas Patocka for finding this.

Fixed a possible hang when reading corrupted non-raw PBM files.

The SDL backend previously had a timer-related bug which could cause
some odd problems. Thanks to Dimitar Zhekov for spotting this one.


** Other changes

The `fullscreen' option now defaults to on, so you now have to use
`--fullscreen=off' (or similar config file option) to disable it. This
keeps the SDL backend's behaviour closer to the svgalib one.


* Changes in zgv 5.8

** New features

Added FreeBSD support, thanks to Radim Kolar for contributing this. Be
sure to read INSTALL in full before building zgv on FreeBSD, there's a
minor problem with it at the moment (nothing too horrible though :-)).

Added support for dithering in 15/16-bit modes. It's slower than I'd
hoped, so it's not enabled by default, but it seems to work well
enough. You can toggle it in the viewer by pressing `F', or add
`dither-hicol on' to a config file. Thanks to Stephane ODUL for
suggesting this.

Added `fullscreen' option, to override possible use of a windowed
display with non-svgalib backends in some situations, the obvious
example being the SDL backend running under X. This isn't necessarily
what you'd want, and has problems like not being able to fill the
screen in modes it doesn't support natively under svgalib. (And SDL
can cause further problems, from what I've seen.)


** Bugfixes

Fixed long-standing bug with interpolation (fix ported from xzgv). In
xzgv the bug could have caused segfaults, but I don't believe this was
the case in zgv due to the way it allocates memory.

Added SDL getbox routine, fixing one of the display glitches when
using that (dialogs not restoring previous screen contents).

Fixed missing-picture-update bug when doing certain mode changes under
SDL.

The SDL backend will now only ever use SDL's non-native-depth mode
emulation for 8-bit modes. This should improve picture quality when
only 8-bit modes are available, and make all modes other than
24/32-bit quite a bit faster. Thanks to David Matthews for inspiring
this change.

The SDL backend is now a lot more sensible about automatically picking
a file selector mode, and should have a better chance of working when
using a single-mode VESA framebuffer. Thanks to David Matthews for
indirectly spotting this problem.

Added timer start/stop to backend code, so now timer-based stuff (most
notably GIF animation) works ok under SDL.

Fixed colour glitches in dialogs under SDL.


** Other changes

Finally changed default installation prefix to /usr/local. `make
install' now removes any old version (both program and documentation)
in the old default locations.

Removed embedded LFs from src/bdf2h.c, which were causing compilation
errors with newer versions of gcc. Not strictly a bug - blame the gcc
folks :-), though to be fair there had been plenty of advance warning.
Thanks to Dimitar Zhekov for the patch.

Moved `fake-cols' toggle key from `F' to `G'.

Removed support for a repeat-timer setting of "-1" (i.e. constantly
reload the image), which had been broken previously anyway.

`x' now aborts GIF animation like Esc does. Thanks to Thomas M. Ott
for pointing out the inconsistency. Note that I don't consider
supporting this slightly pointless alternative to Esc to be terribly
important (e.g. dialogs don't support it and never have, and they've
been in zgv since 1993), and couldn't add it everywhere even if I
wanted to (e.g. change-to-arbitrary-directory dialog).


* Changes in zgv 5.7

** New features

Added support for display backends other than svgalib; currently SDL
is supported. (There are still problems with this - e.g. graphical
glitches with dialog boxes, and broken GIF animation - but it seems to
be mostly working.) Alternative backends are by definition never going
to be *better* than native svgalib, but if you somehow can't use
svgalib then at least this gives you a way of running zgv. Note that
you have to compile a separate zgv executable for each backend, and
only the svgalib one is compiled by default.

New `--auto-mode-fit-diff' option, allows you to specify a pixel
width/height to be disregarded when zgv picks a mode to use and
auto-mode-fit is enabled. So e.g. a 330x250 image would be shown in
320x240 mode if auto-mode-fit-diff is 10. Thanks to Dimitar Zhekov for
this.


** Bugfixes

32-bit modes can now be specified on the command-line (they couldn't
previously). Thanks to "kscott" for spotting this one.

Fixed mouse cursor appearance in 32-bit modes. Thanks to Dimitar
Zhekov for the patch.

No longer sets background colour to black for 1-bit mono PNG files,
where this sometimes caused problems. Thanks to Morten Bo Johansen for
spotting this.


** Other changes

Restored documentation for `-r', `-s', and `-w' options, which was
mistakenly dropped when I added long-option support.


* Changes in zgv 5.6

** New features

New `-A' or `--auto-animate' option, forces the viewer to
automatically animate multiple-image GIF files. Thanks to John
Fitzgerald for suggesting this (more or less). It limits your viewing
options greatly, of course (since it's like pressing `e' every time
you view one, and exiting the image when you exit the animation), but
can be handy for slideshows etc. When this option is enabled, you can
use Backspace/Enter/Space for file navigation/tagging during an
animation. (The skip-to-next-frame key (previously Enter) is now `n'.)

Added multi-file delete. This is on `D', by analogy with `C' and `M'
for copy/move (since it works the same way) - the single-file-only
delete remains available on the Delete key. A new config variable
`delete-tagged-prompt' says whether to prompt before deleting all
tagged files (enabled by default). Thanks to Max Drozdoff for prodding
me into action on this. :-)


** Bugfixes

In the very unusual case of both global and local GIF colourmaps being
present, they were applied in the wrong order. Thanks to Michal Svec
for spotting this.

Should now support 16-bit RGB TGA files. 16-bit palette-based files
*may* also work now, but are untested - it's not all that easy to find
samples of these rather unusual types of TGA file. Thanks to Michal
Svec for spotting the problem.

If a 32-bit mode existed without a corresponding 24-bit mode, and it
was one of the modes which are listed on the viewer right-button menu,
then it was incorrectly `greyed out', i.e. made unavailable from the
menu. Thanks for Dimitar Zhekov for spotting this.

When using `delete-single-prompt off', it previously didn't update the
screen after the deletion. Thanks to Max Drozdoff for spotting this
one.


** Other changes

Added 15/16/24/32-bit 320x240 modes. Thanks to Michal Svec for
suggesting this. Currently only the 24/32-bit mode is selectable
directly (using `^', on the assumption that it's shift-6 - unshifted 6
selects 320x240x8).

Removed `--version-svgalib' option, this was causing trouble when
compiling with old versions of svgalib.


* Changes in zgv 5.5

** New features

Recursive thumbnail update, ported from xzgv. This updates thumbnails
for the current dir and all subdirs (being careful to avoid symlink
loops).

The selector looks different in various ways. Most obviously, the logo
is gone (replaced with a sort of `title bar' with similar content to
xzgv's), the scrollbar is enabled by default, and 20 thumbnails are
visible by default rather than 12 - but there are other changes, like
losing the `raised border' look in most cases, and buttons looking
roughly like they do in GTK+.

GIF animation speed is now much, much more accurate; it previously
tended to run rather slowly.

Now supports GIF animation with the same orientation as the normal
picture. So for example you can flip the picture, and the animation
will be of similarly flipped frames.

The file info dialog (on `:') is much improved - it's now roughly the
same as the one in xzgv.

Added GNU-style long-option support, and changed/reorganised config
file option names to suit this; see `Invoking zgv' in info file or
`OPTIONS' in man page. Essentially things are a lot more xzgv-like now
(and just about everything can be messed about with on the
command-line). Note that most old option names are still supported in
config files, so it shouldn't break things.

Optional black background in 8-bit modes, disabled by default (use the
`black-background' config file option to enable). It works by swapping
the nearest-to-black palette index with the zero index, and altering
the in-memory image to match. This can be rather nice for consistency
with high-colour images, but means that 8-bit images which need such a
`fix' will take longer to appear.


** Bugfixes

Fixed three buffer overruns. Given the nature of these, I suspect they
weren't exploitable for a DoS (i.e. leaving the console in graphics
mode), but it's difficult to be certain.

More BMP fixes - thanks to Jakub Bogusz for most of these.

Finally generates correct height comment for animated GIFs. (Be sure
to remove any old `.xvpics' dir if you want to fix this for existing
files.)

GIF animation with zoom mode enabled no longer pointlessly clears the
screen for each frame.

It previously drew entire pixel lines unnecessarily for images which
remained smaller than the screen width when scaled up.

It didn't previously do the required redraw when toggling fakecols
(with `F') when in 16-colour mode.

No longer undraws/redraws scrollbar unnecessarily during thumbnail
update.

The progress report bar now says "Reading" rather than
"Decompressing". At last. :-)


** Other changes

Message boxes can now pop up over the existing viewer screen in most
cases (i.e. in any mode which is 640x480 or higher and has 256 or more
colours), using much the same approach as the mouse menu does. This
means that e.g. doing `:' in the viewer to get file info generally
doesn't need a mode switch any more.

The old `fullsel', `hicolmodes', and `hicontrol' settings have been
dropped, as they're now obsolete. You get a warning if you try to use
them.

The `centre' setting can no longer be toggled on the command-line with
the `-c' option. (You can use `--centre=off' if you still want to
disable this from the command-line.)


* Changes in zgv 5.4

** New features

Added equivalent of xzgv's zoom-reduce-only option, which lets you
reduce big pictures in zoom mode without it also enlarging small ones.
The toggle is on Alt-r, and the config file option is
`zoom_reduce_only'. Thanks to Jan Blasiak for this.

You can now optionally use a magic-number-based scheme to choose which
files to list in the selector (Alt-m toggles it, and `fsmagic' is the
relevant config file option). This approach is much slower, but useful
when you have files lacking extensions. Thanks to Dank